1. Field of the Invention
The present invention is related to a boot with a flexible upper, especially intended for snowboarding.
2. Description of Background and Relevant Information
There are two broad categories of snowboarding boots: one has a rigid plastic shell equipped with a flexible inner liner, and the other has a flexible, or partially flexible upper, made of fabric, leather or flexible plastic. The first category is not really adapted to the modern practice of snowboarding because the practitioners are often required to move while walking on snow. The invention is related to the second category of flexible boots that is better adapted to walking. These days, these shoes or boots are essentially designed as simple, lengthy boots, that are impervious and comfortable but devoid of any effective role in the transmission of forces that is associated with the dynamic practice of the discipline. In the majority of cases, these boots are adapted to so-called "shell" bindings that comprise a base on which the sole and a dorsal element linked to the base rest, and that provides a rigid rear support to the lower part of the leg, especially when the snowboarder makes back side turns. Straps in sufficient numbers ensure the tightening of the boot in the binding.
These systems have disadvantages. They are cumbersome because of the rear ascending element and because of the presence of the straps. The straps must be readjusted each time that the boot is reengaged into the "shell" binding, before each descent. The tightening of the straps must be adequate in order to retain the boot efficiently; this causes problems of comfort due to the flexibility of the upper. Finally, these shells transmit the various combined bending forces badly because the adaptation of their shapes is often approximate, this being especially true for the dorsal element with the boot, and this is not adequately rectified by tightening the straps.
Various binding systems, called "step-in" systems evolved in order to replace the shell bindings, and these consist of connecting one or several gripping elements linked to the sole of a flexible boot to an automatic latching system affixed on the board. Such an example of a "step-in" binding is described in the application WO 95/09035. For the transmission of forces, the flexible boot is subject to a localized reinforcement, especially in order to ensure rear support.
The document FR 2 722 371 is related to this type of boot that comprises a flexible and deformable inner liner portion, an impermeable and flexible outer upper portion and, located between these two portions, a more rigid shell element on which is journalled, along an axis passing through the median longitudinal plane of the boot, a journalled dorsal element that encloses a portion of the calf. This type of boot has the advantage of being more efficient when the snowboarder makes back side turns due to the fact that the dorsal element is inserted into the structure of the boot, while also promoting a certain lateral looseness, either on the inner or outer side, so as to allow the snowboarder to adopt leg positions that are more or less bent laterally with respect to his torso.
The document EP-A1-646334 is also related to a boot with an inner frame having a journalled dorsal part. In the example described, the boot is connected to a base in the form of a plate and the tightening on this base is done by straps. This solution thus picks up on some of the disadvantages of strap bindings.
The patent application FR 2 719 197 suggests another solution consisting of a boot with a flexible upper and a rigid, journalled, outer frame. The principle of construction for such a boot enables it to be adapted onto any type of binding, including traditional board bindings for lengthy, rigid shell boots that are derived from downhill skiing.
All these solutions for boots are interesting because they offer a rear support in "back side" turns, as well as internal, lateral flexibility for figures, jumps, etc. However, when the snowboarder is in the position of relaunching his board, or in the skating phase, he requires a certain external lateral support. This asymmetry in the external/internal (i.e., lateral/medial) functions is not dealt with in the known prior art solutions.